The effect of temperature on the properties of hydroxyapatite precipitatedfrom calcium hydroxide and phosphoric acid

The effect of temperature on stoichiometry, morphology and crystallinity of hydroxyapatite (HA) prepared from calcium hydroxide and phosphoric acid wa s investigated. The crystals precipitated in the temperature range 22-95 degreesC and matur ed for 20 h at precipitation temperature have shown the properties of therm ally stable HA. The size and crystallinity of the crystals increase with an increase of the preparation temperature. HA precipitated at 95 degreesC shows thermal stability even without ripenin g. The importance of the maturation stage in obtaining thermally stable HA increases with decreasing precipitation temperature, HA precipitated at low temperature (22 degreesC) after appropriate maturati on shows the properties of stoichiometric low crystalline HA and appears to be very promising as a bioceramic precursor. (C) 2001 Elsevier Science B.V . All rights reserved.